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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #305626

Title: Satellite-based crop coefficient and regional water use estimates for Hawaiian sugarcane

Author
item Zhang, Huihui
item Anderson, Raymond - Ray
item Wang, Dong

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2015
Publication Date: 6/23/2015
Citation: Zhang, H., Anderson, R.G., Wang, D. 2015. Satellite-based crop coefficient and regional water use estimates for Hawaiian sugarcane. Field Crops Research. 180:143-154.

Interpretive Summary: Satellite remote sensing offers an alternative means of water management on a regional scale, but algorithms are needed for applying the technology for specific applications. Using satellite Landsat 7 images and a set of ground-based plant and meteorological measurements, near real time sugarcane water use was assessed by developing statistical relationships between plant canopy size and both crop coefficient and evapotranspiration. The findings should be directly useful for farm irrigation management, and the approach can be applied to other farming systems for improving regional and on-farm water management.

Technical Abstract: Water availability is a major limiting factor for sustainable production of potential biofuel crops in Maui, Hawaii. It is essential to improve regional, near-real time estimates of crop water use to facilitate optimal water management. Satellite remote-sensing offers multiple methods to estimate water management, however most approaches assume a spatially homogeneous regional meteorology, which does not apply in Hawaii. Canopy ground cover and spectral reflectance were measured over two sugarcane fields on satellite Landsat 7 overpass dates. A strong linear relationship between satellite-based Normalized Difference Vegetation Index (NDVI) values and canopy ground cover was found (R2 = 0.97). Canopy ground cover was also found highly correlated to crop coefficient (Kc) which was calculated from reference evapotranspiration (ET0) and sugarcane crop evapotranspiration (ETc) observations from Eddy Covariance towers. Spatial ET0 for the entire sugarcane plantation was determined from an automated weather station network previously installed by the commercial grower of the plantation. Regressions were used to convert satellite NDVI to Kc maps, and then the satellite-based ETc maps were developed from the satellite-based Kc maps and ET0 values from the weather station network. To compare with the satellite-based crop coefficient/reference ET method, ETc and Kc were also estimated using a satellite-based surface energy balance technique, the METRIC model. These two satellite-based methods were correlated fairly well (R2 = 0.84 for Kc and 0.81 for ETc). Compared to METRIC model, the satellite-based crop coefficient/reference ET method may be more practicable for estimating crop water use in Maui, where ground-based ET0 measurements are available through the on-site automated weather station network.